High-resolution integrated stratigraphy of the upper Burdigalian-lower Langhian in the Mediterranean: the Langhian historical Stratotype and new candidate sections for defining its GSSP

Results of integrated high-resolution stratigraphic studies (calcareous plankton and magnetostratigraphy) of three Mediterranean sections (La Vedova in Central Italy, Contrada Pesciarello in Sicily and St. Peter’s Pool in Malta) and one deep-sea core from the mid-latitude North Atlantic (DSDP Hole 608) are here synthesized. They are compared with those of previously studied deep marine sections in the Mediterranean including the historical stratotype, with the aim to select the most suitable section and criterion to define the Langhian GSSP (Global Stratotype Section and Point). This study significantly improves the existing magneto-biostratigraphic framework for the upper Burdigalianlower Langhian and opens new perspectives for defining the Langhian GSSP. The two guiding criteria to recognize the base of the Langhian, i.e. the Praeorbulina datum and the top of Chron C5Cn.1n, can not be applied together, as these two events differ in age by ~740 kyr. The selection of either of these two criteria will imply a different duration for the Langhian: relatively short, in case the Praeorbulina datum is selected, or longer and probably more acceptable, in case the top of Chron C5Cn.1n is selected. The primary calcareous plankton events which, according to our data, appoximate the top of Chron C5Cn.1n, are the Last Common Occurrence (LCO) of the calcareous nannofossil Helicosphaera ampliaperta and the LCO of the planktonic foraminifer Paragloborotalia bella. Other calcareous plankton events have been recorded close to the same magnetic reversal, such as a short influx of H. ampliaperta (Ia1) and the Paragloborotalia siakensis Acme0. The Paragloborotalia siakensis AcmeaEnd (AaE) and the Sphenolithus heteromorphus Paracme End (PE) represent the primary plankton events associated with the Praeorbulina datum. On the basis of magneto-biostratigraphic results two of the three studied Mediterranean sections (La Vedova and St. Peter’s Pool), each from a different point of view, are potentially suitable to be proposed as candidates for the definition of the Langhian GSSP. 137 Climate changes, bioevents and geochronology in the Atlantic and Mediterranean over the last 23 Myr Joint RCMNS - RCANS Interim Colloquium, Salamanca. September 21st to 23rd, 2011